Novel syntheses of camptothecin alkaloids. Part I. Intramolecular [4+2] cycloadditions of N-arylimidates and 4H-3,1-benzoxazin-4-ones as 2-aza-1,3-dienes was written by Fortunak, Joseph M. D.;Mastrocola, Antonietta R.;Mellinger, Mark;Sisti, Nicolas J.;Wood, Jeffery L.;Zhuang, Zhi-Ping. And the article was included in Tetrahedron Letters in 1996.Safety of Ethyl 5-cyano-4-methyl-6-oxo-1,6-dihydropyridine-2-carboxylate The following contents are mentioned in the article:
Intramol. [4+2] cycloadditions of both N-arylimidates and (4H)-3,1-benzoxazin-4-ones acting as 2-aza-1,3-dienes were described. Reaction with unactivated alkynes lead to pyrrolo[3,4-b]quinolines containing the ABC ring system of camptothecin. E.g., 10-methoxycamptothecin precursor I was prepared by intramol. [4+2] cycloaddition of a 4:1 isomeric mixture of O-methylimidate II (R = 4-MeOC6H4), which had been prepared by Me3OBF4 O-methylation of the corresponding N-(4-methoxyphenyl)-amide, followed by elimination of methanol. This study involved multiple reactions and reactants, such as Ethyl 5-cyano-4-methyl-6-oxo-1,6-dihydropyridine-2-carboxylate (cas: 58610-61-0Safety of Ethyl 5-cyano-4-methyl-6-oxo-1,6-dihydropyridine-2-carboxylate).
Ethyl 5-cyano-4-methyl-6-oxo-1,6-dihydropyridine-2-carboxylate (cas: 58610-61-0) belongs to pyridine derivatives. Pyridine has a dipole moment and a weaker resonant stabilization than benzene (resonance energy 117 kJ路mol鈭? in pyridine vs. 150 kJ路mol鈭? in benzene). Several pyridine derivatives play important roles in biological systems. While its biosynthesis is not fully understood, nicotinic acid (vitamin B3) occurs in some bacteria, fungi, and mammals.Safety of Ethyl 5-cyano-4-methyl-6-oxo-1,6-dihydropyridine-2-carboxylate